JPH0743369A - Analyzer with liquid level sensor - Google Patents

Abstract

PURPOSE:To ensure detection of liquid level by coating the outer periphery of a dispenser probe, except one end thereof, and the inner/outer peripheries of a metal pipe with insulation coating and sustaining a stabilized insulation resistance between the dispenser probe and an outer peripheral conductor thereby eliminating the influence of disturbing elements. CONSTITUTION:A dispenser probe 8 is coated on the outer periphery, except the forward end thereof, with a dielectric coating material 6 in order to increase the surface resistance and connected with a liquid level detecting substrate. The probe 8 is further covered with an insulating material 7 which is covered with a metal pipe 5 having coated inner and outer peripheries. The metal pipe 5 is grounded and the probe 8 is shielded except the forward end thereof so that it is not susceptible to disturbance noise. Since the outer periphery of the probe 8 and the inner/outer peripheries of the metal pipe 5 are applied with coating 6, insulation resistance between the probe 8 and the metal pipe 5 does not decrease even if the surface resistance of the insulation material 7 decreases due to adhesion of liquid to the entire probe resulting in the stabilized shielding effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analyzer having a dispensing mechanism having a liquid level detecting function, and more particularly to detecting a liquid level from a change in capacitance when a dispensing probe comes into contact with the liquid level. Regarding analytical equipment.

[0002]

2. Description of the Related Art As a technique related to the present invention, particularly a technique to which the present invention can be applied, as a prior art for detecting the liquid level by detecting the capacitance in a liquid container with a single dispensing probe, JP-A-62-218818 and U.S. Pat. No. 4,970,
No. 468 is known.

[0003]

Since the conductive portion of the metal dispensing probe used in the capacitance type liquid level sensor is the entire dispensing probe, it is affected by disturbance noise and stray capacitance by the outer conductor. Although there is no configuration, the insulation resistance between the dispensing probe and the outer conductor may be disturbed by a disturbance element due to dirt adhering to the surface of the insulating material inserted between the dispensing probe and the outer conductor, or moisture absorption of the insulating material. It had the potential to change rapidly. An object of the present invention is to provide an analyzer that constantly maintains the insulation resistance between the dispensing probe and the outer peripheral conductor, blocks the influence of disturbance elements, and reliably detects the liquid level of the liquid in the container.

[0004]

According to the present invention, the outer periphery of the dispensing probe excluding one end and the inner and outer periphery of the metal tube are coated with an insulating coating.

[0005]

[Function] Since the metal dispensing probe is entirely covered by the outer metal tube except the tip of the dispensing probe, which is a few centimeters (cm), through the insulating material, the insulation resistance between the dispensing probe and the metal tube is DC. The resistance value is finite but large enough to be ignored (generally, when DC500V is applied, 1
000 MΩ or more), and the dispensing probe and the metal tube are insulated.

However, in the case of the configuration to which the present invention is not applied,
If water suitability or dirt adheres to the entire circumference of the probe, the surface resistance of the entire circumference of the probe decreases, and the insulation resistance between the dispensing probe and the metal tube decreases.

When the probe according to the present invention is used, the insulation resistance between the probe and the metal tube is maintained even if water suitability or dirt adheres to the entire circumference of the probe, and a stable shield effect due to the metal tube is obtained. It is possible to reliably detect the electrostatic capacity of the liquid inside and to reliably detect the liquid level in the sample container.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a structural diagram of a sensor-integrated probe 10 according to the present invention.

The dispensing probe 8 is coated on its outer periphery with an insulating coating material 6 except the tip of several mm (millimeters) to increase the surface resistance of the outer periphery of the dispensing probe 8.

Further, the dispensing probe 8 is connected to the liquid level detection substrate, and the liquid level detection substrate controls the liquid level detection operation of the sampling mechanism 1.

The outer circumference of the dispensing probe 8 is covered with an insulating material 7, the outer circumference of the insulating material 7 is coated with an insulating coating material 6 on the inner and outer circumferences, and is covered with a metal tube 5 having an increased surface resistance on the inner and outer circumferences.

The metal tube 5 is connected to GND (ground), and the tip of the dispensing probe 8 is several cm (centimeter).
Other than the above, the structure is shielded by the metal tube 5 and is not affected by disturbance noise or stray capacitance.

FIG. 2 shows an external view when the tip of the sensor-integrated probe 10 is dipped in a liquid 12 such as water, a sample or a reagent.

When the entire outer circumference of the probe 10, particularly the tip portion, is suitable for water, dirt, etc., the outer circumference of the dispensing probe 8 and the inner and outer circumferences of the metal tube 5 are insulated in the dispensing probe 8 according to the present invention. Since it is coated with the coating material 6, the insulation resistance between the dispensing probe 8 and the metal tube 5 does not decrease even if the surface resistance of the insulation material 7 decreases due to the adhesion of the liquid 12.

When the outer circumference of the dispensing probe 8 and the inner and outer circumferences of the metal tube 5 are not coated with the insulating coating material 6, the surface resistance of the insulating material 7 is lowered due to the adhesion of the liquid 12, and the dispensing probe 8- There is a possibility that the insulation resistance between the metal tubes 5 will drop sharply.

FIG. 3 is a schematic diagram of the dispensing mechanism of the automatic analyzer to which the present invention is applied.

The sampling arm 2 of the sampling mechanism 1 rotates up and down, and the probe 10 attached to the sampling arm 2 detects the liquid level of the sample 4 in the sample container 3 placed on the sample disk 9 and sucks and discharges it. Take action.

FIG. 4 is a configuration diagram when measuring the insulation resistance characteristic between the dispensing probe and the metal tube.

In FIG. 4, the test tube 11 is used as the sample container 3, the inner wall of the test tube 11 is wet by the sample 4, and the probe 10 moves inside the test tube 11 in a high humidity state. Dispensing probe 8-metal tube 5 when descending
The measurement figure of the amount of insulation resistance fluctuations between is shown.

When the probe 10 descends and the tip of the dispensing probe 8 passes the upper part of the test tube 11 at x ₃ , the probe 10 further descends, and the tip of the dispensing probe 8 becomes the test tube 1.
The position where the inner wall of 1 passes through the wet part is x ₂ , the probe 10 further descends, and the tip of the dispensing probe 8 becomes the test tube 1
The position within 1 in contact with the sample 4 is x ₁ .

FIG. 5 shows the characteristics of R (insulation resistance between dispensing probe and metal tube) -X (distance between dispensing probe tip and lower part of container).

If water droplets, oxide film, or other dirt is attached to the entire outer circumference of the probe 10, the dirt attached to the outer circumference of the probe 10 is affected by the atmosphere in the test tube 11 and the dispensing probe 8 is used. The insulation resistance between the metal tubes 5 decreases as the tip position of the dispensing probe 8 becomes x ₃ , x ₂ , x ₁ and the lower part of the test tube 11.

Similarly to the probe 10 according to the present invention, the test tube 1 is prepared by attaching dirt such as water droplets or oxide film to the entire outer periphery.
If the test tube 1
Even if the surface resistance of the entire outer periphery of the probe 10 is reduced due to the influence of the atmosphere inside the pipe 1, the insulation between the dispensing probe 8 and the metal tube 5 is reliably maintained by the insulating coating material 6. The insulation resistance between the dispensing probe 8 and the metal tube 5 always keeps a constant resistance value without being affected by disturbance.

Therefore, according to the present invention, the dispensing probe 8-
A stable insulation resistance value can always be obtained between the metal tubes 5, and a stable shielding effect of the dispensing probe 8 by the metal tubes 5 can be obtained.

[0026]

As described above, according to the present invention, it is possible to prevent the insulation resistance between the dispensing probe and the metal tube from being lowered due to the influence of water suitability, dirt attached to the entire circumference of the probe, and the atmosphere of disturbance. Since the shielding effect of the dispensing probe by the metal tube is always maintained, the sample and the liquid level in the reagent container can be detected reliably and stably, and the reliability is greatly improved. It is possible to contribute to.

[Brief description of drawings]

FIG. 1 is a structural diagram of a probe according to an embodiment of the present invention.

FIG. 2 is an external view when the dispensing probe according to the present invention is immersed in a liquid.

FIG. 3 is a diagram for explaining the operation of the embodiment of the present invention.

FIG. 4 is an insulation resistance characteristic diagram between the dispensing probe and the metal tube when the inner wall of the sample container is wet with a liquid.

FIG. 5 is also an insulation resistance characteristic diagram.

[Explanation of symbols]

5 ... Metal tube, 6 ... Insulation coating material, 7 ... Insulation material, 8
… Dispensing probe.

Claims (1)

[Claims] 1. A probe for dispensing a liquid from a liquid containing container containing a sample or a reagent liquid to a reaction container is used as a liquid level detecting electrode, and when the probe comes into contact with the liquid in the liquid containing container, the liquid In an analyzer configured to detect a surface, a liquid level sensor characterized by insulatingly coating the inner and outer circumferences of a metal tube configured to cover a portion other than the tip of the probe through an insulating material on the outer circumference of the probe. Equipped analyzer.